Valve plate assembly for a molten metal slide gate valve

ABSTRACT

An improved valve plate assembly is provided for use in a slide gate valve. The valve plate assembly includes a refractory valve plate having an orifice positioned along its longitudinal centerline, and truncated corners for optimizing the clamping forces to reduce and/or contain cracking caused by thermal expansion. The size and shape of the plate is defined by the design maximum design orifice diameter and the service the plate is designed to address.

RELATED APPLICATIONS

This application claims priority to U.S. Patent Application No. 61/540,296, having a filing date of Sep. 28, 2011, which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

The present invention generally relates to valve plates for use in slide gate valves for controlling a flow of molten metal. More specifically, the present invention relates to a valve plate assembly that is resistant to cracks caused by thermal stresses while minimizing the amount of materials used to accomplish the task.

Slide gate valves are used to control the flow of molten metal in steelmaking and other metallurgical processes. For some slide gate valves where plates are exchanged sequentially during pouring, an upstream stationary plate is used in conjunction with exchangeable downstream plates. Such valves often comprise a main frame, an upstream stationary plate, and a movable exchangeable plate. The upstream stationary plate includes an orifice that is in registry with a metallurgical vessel for conducting the flow of molten metal. The movable exchangeable plate includes a flow conducting orifice that is downstream of the upstream stationary plate and which, may be moved into or out of alignment with the orifice of the upstream stationary plate as the moveable plate is moved between open and closed positions. In some processes, the slide gate valve also incorporates a stationary downstream exchangeable plate that has a flow conducting orifice that is substantially aligned with an orifice of the upstream stationary plate, and which may also be part of the pouring orifice. When aligned, the orifices of the upstream, downstream, and/or moving plate provide a pouring orifice through which the molten metal may flow. The rate of flow of molten metal during pouring may be dependent upon the position of a stopper upstream of the upstream stationary plate, the orifice size of the moveable exchangeable plate, and/or the misalignment of the orifice of the movable exchangeable plate with the orifice of the upstream stationary plate.

The moving plate in a three plate reciprocating system is typically identical in size or larger than the downstream stationary plate so as to allow the downstream stationary plate to be exchanged during valve servicing without requiring disassembly of the valve mechanical parts. The moving plate is typically driven, either directly or through mechanical linkage, by hydraulic actuators. In slide gate valves where plates are exchanged sequentially during pouring, a stationary upstream plate may be used in conjunction with exchangeable downstream plates.

If the refractory valve plate, such as the upstream, downstream, and moving plates, is sized by multiples of the maximum design orifice diameter, the shutoff stroke of the valve, and the ferrostatic head, that is, the depth of molten metal in the molten metal containing vessel that is upstream of the upstream valve plate, may be optimized for the service. The maximum design orifice diameter is the maximum orifice size that a plate is designed to operably accommodate. The orifice may have a number of different sizes and shapes that do not exceed circumscription within the maximum design diameter orifice for the plate. Yet, the plate may be used in non-aggressive service applications, such as teeming molten iron and re-ladle operations, among others, with an orifice that exceeds the maximum design orifice diameter if the plate is subjected to minimum re-use.

The size of the plate may be reduced based upon considerations of the plate's particular use. For example, accounting for the ferrostatic head in the design of the plate may allow for a reduction in the amount of material used in the plate, which may lead to not only a reduction in the size and weight of the plate, but also a reduction in size of related components used to support and/or drive the plate. Moreover, a small increase or decrease in the outer dimensions of the plate may allow for a relativity larger increase or decrease in the volume of material in the plate. For example, higher ferrostatic heads can lead to greater molten metal pressure that must be contained by the orifice and sealed at the plate face. High ferrostatic environments are defined as those where the ferrostatic head exceeds 2.0 meters. Low ferrostatic head environments are defined as those where the ferrostatic head is 2.0 meters or less. Because of the differences in pressures in high and low ferrostatic head applications, the refractory plates for higher ferrostatic heads may have greater edge margins between the orifice of the plate and the edges of the plate than plates for low ferrostatic head applications. Thus, when a higher ferrostatic head plate is used in low ferrostatic head applications, there is an unnecessary excess of edge margin, and therefore unnecessary material, being used that adds weight and expense to the plate. Further, unnecessary material involves more than wasting raw material. A plate that is larger than it needs to be for the service may have more impact on the environment than one that is more suitably sized for the service. For example, it may take more energy to mix the material, more energy to fire the material, more energy and diamond abrasive to finish the surface of the plate, and generates more refractory swarf that must be disposed of as a hazardous waste. Furthermore, use of unnecessarily oversized plates may also result in the use of corresponding oversized components, such as drive and support frames for the oversized plates, which may further add unnecessary costs to the system.

Both the stationary plates and the moving plate of such sliding gate valves are formed from heat and erosion resistant refractory materials, such as aluminum oxide, magnesium oxide, alumina carbon, magnesia carbon, and zirconium oxide. However, despite the heat and erosion resistance of these materials, the severe thermally induced stresses such plates are subjected to may ultimately cause some degree of cracking to occur. For example, in steelmaking each plate can be subjected to temperatures of 1600° C. at the area immediately surrounding the flow-conducting orifice while its exterior edges are experiencing ambient temperature. The resulting large thermal gradient creates large mechanical stresses in the plate. The area around the pouring orifice expands significantly more than the outside edges of the plate. This generates compressive stresses around the orifice and tensile stresses at the edges. Since refractory materials have relatively low tensile strength, cracks develop at the edges and propagate towards the orifice. If nothing is done to constrain the plate the cracks may migrate all the way to the orifice creating a path for air to enter the metal stream or metal to leak to the outside of the plate.

To prevent the spreading of such cracks and the consequent breakage of the plate or leakage of gas or metal, various constraint methods have been developed in the prior art. The purpose of these mechanisms is to apply sufficient pressure around the perimeter of the plate so that cracks emanating from the edges do not spread to the orifice. In one such mechanism, a steel band is stretched around the perimeter of each of the valve plates. Unfortunately, there are at least three disadvantages associated with the use of such band-type clamping mechanisms. First, the steel that forms such bands is a superior thermal conductor to the air that would otherwise surround the plate edges; the use of the steel band actually increases the thermal gradient from the edges of the plate to the orifice, thereby encouraging even more cracking to occur. Secondly as the band heats up as a result of being in intimate contact with the refractory, it expands much more than the refractory material forming the plate, which in turn causes the band to relax the compressive forces it needs to apply around the plate in order to discourage the spread of cracks. Thirdly, if the corners of the plate are not rounded, such clamping bands can apply localized mechanical stresses into the corners of the plate, which in turn can cause unwanted cracking in these areas.

BRIEF SUMMARY OF THE INVENTION

One aspect of the present invention is an improved common valve plate for controlling a flow of molten metal in a slide gate valve. The common valve plate includes a refractory plate having an orifice, a first and second long side, a first and second shutoff end truncated corners, a shutoff end, a first and second orifice end truncated corner, a short side orifice end, a shut off margin circle, and a longitudinal centerline. The orifice is configured to allow molten metal to flow through the refractory plate, the center of the orifice being positioned at the intersection of the longitudinal centerline and a transverse orifice centerline. The first and second long sides are parallel to the longitudinal centerline, the first and second long sides being positioned at opposite sides of the longitudinal centerline at a distance of approximately 1.125 to 1.50 times the maximum design orifice diameter. The short side shutoff end is approximately 1.0 times the maximum design orifice beyond a transverse shutoff centerline. The transverse shutoff centerline is perpendicular to the longitudinal centerline and is positioned approximately at the shutoff stroke distance, typically 1.5 to 2.5 times the maximum design orifice diameter from the transverse orifice centerline. The shutoff stroke can be any distance that is greater than the maximum design orifice diameter. The shutoff stroke is typically not less than 12 mm greater than the maximum design orifice diameter, and not more than 3.0 maximum design orifice diameters in length.

Additionally, the short side orifice end is located at an end of the refractory plate opposite of that of the short side shutoff end. The short side orifice end is approximately 1.625 to 2.0 times the maximum design orifice diameter away from the transverse orifice centerline at an end of the refractory plate opposite that of the short side shutoff end. The length of the plate the sum of the shut off stroke plus the distance from the centerline of the orifice to the short side orifice end plus the distance from the centerline at shutoff to the short side shutoff end. The shutoff margin circle provides an area sufficient to prevent molten metal from an upstream orifice that is adjacent to the refractory plate from flowing around the first and second sides or truncated sides. The shutoff margin circle is centered at the intersection of the longitudinal centerline and transverse shutoff centerline and has a diameter that is approximately 2.0 times the maximum design orifice diameter. Further, the first and second shutoff truncate corners are positioned at the shutoff end of the refractory plate, the first truncated shutoff corner being defined by a first line that extends from the intersection of the first long side and the transverse shutoff centerline, is tangent to the shutoff margin circle and proceeds until the first line intersects the short side shutoff end. The second truncated shutoff corner is defined by a second line that extends from the intersection of the second long side and the transverse shutoff centerline, is tangent to the shutoff margin circle and proceeds until the second line intersects the short side shutoff end. The first and second orifice end truncated corners are positioned at the orifice end of the refractory plate. The first and second orifice end truncated corners extend from the intersection of the first and second long sides, respectively, and a second transverse construction line until intersecting the short side orifice end. The first orifice end truncated corner is perpendicular to a first orifice end construction line. The second orifice end truncated corner is perpendicular to a second orifice end construction line. The second transverse construction line is approximately 0.5 times the maximum design orifice diameter away from a first transverse construction line that is approximately 1.0 to 1.5 times the maximum design orifice diameters inside the short side orifice end. The first orifice end construction line extends from the intersection of the longitudinal centerline and the first transverse construction line and through the intersection of the second transverse construction line and a first primary longitudinal construction line. The first primary longitudinal construction line is approximately 0.25 times the maximum design orifice diameter inside the first long side. The second orifice end construction line extends from the intersection of the longitudinal centerline and the first transverse construction line and through the intersection of the second transverse construction line and a first secondary longitudinal construction line. The first secondary longitudinal construction line is approximately 0.5 times the maximum design orifice diameter inside the second long side.

Another aspect of the present invention is an improved symmetrical valve plate for controlling a flow of molten metal in a slide gate valve. The symmetrical valve plate includes a refractory plate having an orifice, a longitudinal centerline, a transverse orifice centerline, a first and a second symmetrical end, a first and second long side. The transverse centerline is positioned along said longitudinal centerline at a distance of the shutoff stroke from the transverse centerline at the orifice on either side of said centerline at orifice. The first and second long sides are located on opposite sides of the longitudinal centerline. Further, the first and second long sides are positioned approximately 1.125 to 1.50 times the maximum design orifice diameter away from the longitudinal centerline.

The first and second symmetrical ends of the refractory plate are divided generally at the transverse centerline at orifice. Further, the first and second symmetrical ends are each configured to stop the flow of molten metal from an adjacent upstream orifice. The first and second symmetrical ends both have a first and second truncated side, a transverse shutoff centerline, and a short side shutoff end. The short side shutoff ends of the first and second symmetrical end are separated by a distance of equal to approximately twice the shutoff stroke plus 1.0 times the maximum design orifice diameter beyond the shutoff stroke on both ends. The transverse shutoff centerline is positioned approximately 1.50 to 2.0 times the maximum design orifice from the transverse orifice centerline. Additionally, for both the first and second side symmetrical ends, the first and second truncated sides are joined to short side shutoff end by truncated corners. The truncated corners are tangent to a circle having a diameter 2.0 times the maximum design orifice diameter that is located at the intersection of the longitudinal centerline and the transverse shutoff centerline. The truncated corners extend from the intersection of transverse shutoff centerlines and the first and the second long sides, and extend to the short side shutoff end.

Another aspect of the present invention is an improved moving valve plate for controlling a flow of molten metal in a slide gate valve. The moving valve plate includes a refractory valve plate having an orifice, a first and a second long side, a short side shutoff end, a short side orifice end, a first and a second shutoff truncated corners, and a first and second orifice end truncated corners. The orifice is configured to allow molten metal to flow through the refractory plate. The center of the orifice is positioned at the intersection of the longitudinal centerline and a transverse orifice centerline. The first and second long sides are parallel to the longitudinal centerline. Further, the first and second long sides are positioned at opposite sides of the longitudinal centerline at a distance of approximately 1.50 to 1.75 times the maximum design orifice diameter. The short side orifice end is approximately 1.25 to 1.375 times the maximum design orifice diameter beyond a transverse centerline at the orifice. The transverse shutoff centerline is perpendicular to the longitudinal centerline and positioned approximately 1.5 to 2.5 times the maximum design orifice diameter from the transverse orifice centerline. The short side shutoff end located at an end of the refractory plate that is opposite of that of the short side orifice end, the short side shutoff end is approximately 1.75 to 2.125 times the maximum design orifice diameter from the transverse shutoff centerline.

Additionally, the first and second orifice end truncate corners are positioned at the short side orifice end of the refractory plate. The first and second orifice end truncated corners are tangent to a circle that is located at the intersection of the longitudinal centerline and the transverse orifice centerline, the circle being tangent to the short side orifice end and having a diameter of approximately 2.50 to 2.75 times the maximum design orifice diameter.

Further, the first and second shutoff end truncated corners are positioned at the shutoff end of the refractory plate. The first and second shutoff end truncated corners extend from the intersection of the first and second long sides, respectively, and a third transverse construction line until intersecting the short side shutoff end. The first shutoff end truncated corner is perpendicular to a first shutoff end construction line. Similarly, the second shutoff end truncated corner is perpendicular to a second shutoff end construction line. The third transverse construction line is approximately 1.125 to 1.50 times the maximum design orifice diameter away from the transverse shutoff centerline toward the short side shutoff end. The first shutoff end construction line extends from the intersection of the longitudinal centerline and a second transverse construction line and through the intersection of the third transverse construction line and a first primary longitudinal construction line. Additionally, the first longitudinal construction line is approximately 0.25 times the maximum design orifice diameter inside the first long side. The second transverse construction line is approximately 0.375 to 0.5 times the maximum design orifice diameter from the transverse shutoff centerline toward the short side shutoff end. The second shutoff end construction line extends from the intersection of the longitudinal centerline and a second transverse construction line and through the intersection of the third transverse construction line and a first secondary longitudinal construction line.

A further aspect of the present invention is an improved stationary plate for controlling a flow of molten metal in a slide gate valve. The stationary plate includes a refractory valve plate having an orifice, a first and a second long side, an entrance end, an exit end, a first and a second entrance end truncated corners, and a first and second exit end truncated corners. The orifice is configured to allow molten metal to flow through the refractory plate. The center of the orifice is positioned at the intersection of the longitudinal centerline and a transverse orifice centerline. The first and second long sides are parallel to the longitudinal centerline. Additionally, the first and second long sides are positioned at opposite sides of the longitudinal centerline at a distance of approximately 1.125 to 1.25 times the maximum design orifice diameter.

The entrance end is approximately 1.625 to 1.875 times the maximum design orifice beyond a transverse orifice centerline. Further, the exit end is positioned at an end of the refractory plate that is opposite of that of the entrance end. The exit end is approximately 1.50 to 1.625 times the maximum design orifice diameter from the transverse orifice centerline. The first and second entrance end truncate corners are positioned at the entrance end of the refractory plate.

The first and second entrance end truncated corners are tangent to a circle that is located at the intersection of the longitudinal centerline and a first transverse construction line. The circle has a diameter of approximately 2.0 times the maximum design orifice diameter. The first transverse construction line is generally perpendicular to the longitudinal centerline and positioned approximately 1.0 times the maximum design orifice diameters inside the entrance end. The first entrance end truncated corner extends from the intersection of the first transverse construction line and the first long side to the tangency with the circle and extends until the first entrance end truncated corner intersects with the entrance end. The second entrance end truncated corner extends from the intersection of the first transverse construction line and the second long side to the tangency with the circle and extends until the second entrance end truncated corner intersects with the entrance end orifice end.

The first and second exit end truncated corners are positioned at the exit end of the refractory plate. The first and second exit end truncated corners extend from the intersection of the first and second long sides, respectively, and a third transverse construction line until intersecting the exit end. Additionally, the first exit end truncated corner is perpendicular to a first exit end construction line, while the second exit end truncated corner is perpendicular to a second exit end construction line. The third transverse construction line is approximately 0.50 times the maximum design orifice diameter away from the second transverse construction line exit end toward the transverse orifice centerline. The first exit end construction line extends from the intersection of the longitudinal centerline and a second transverse constructive line and through the intersection of the third transverse construction line and a first primary longitudinal construction line. The first longitudinal construction line is approximately 0.25 times the maximum design orifice diameter inside the first long side. The second transverse construction line is approximately 1.0 to 1.25 times the maximum design orifice diameter from the exit toward the entrance end. The second exit end construction line extends from the intersection of the longitudinal centerline and a second transverse construction line and through the intersection of the third transverse construction line and a first secondary longitudinal construction line. The second longitudinal construction line is approximately 0.25 times the maximum design orifice diameter inside the second long side.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a longitudinal section view of a three plate reciprocating valve having a changeable pour tube and plate clamping, or driving, components.

FIG. 2 is a view taken along line 2-2 of FIG. 1 illustrating an upstream face of a downstream stationary plate, a downstream plate fixed clamp, and a downstream plate movable clamp.

FIG. 3 is a view taken along line 3-3 of FIG. 1 showing the upstream face of a moving plate, a moving plate drive frame, and a moving plate clamp.

FIG. 4 is a plan view demonstrating the development of a high head common plate for high head applications according to an embodiment of the present invention.

FIG. 5 is a plan view demonstrating the continued development of the shape and configuration of the high head common plate shown in FIG. 4 according to an embodiment of the present invention.

FIG. 6 is a plan view of a high head common plate according to embodiments of the present invention.

FIG. 7 is a plan view of a high head common plate with a radiused shutoff end according to an embodiment of the present invention.

FIG. 8 is a plan view demonstrating the development of a common plate for low head applications according to an embodiment of the present invention.

FIG. 9 is a plan view of a low head common plate according to an embodiment of the present invention.

FIG. 10 is a plan view illustrating the development of a symmetrical plate for high head applications according to an embodiment of the present invention.

FIG. 11 is a plan view of a symmetrical plate for high head applications according to an embodiment of the present invention.

FIG. 12 is a plan view illustrating the development of a symmetrical plate for low head applications according to an embodiment of the present invention.

FIG. 13 is a plan view of a symmetrical plate for low head applications according to an embodiment of the present invention.

FIG. 14 is a plan view illustrating the development of a moving plate for high head applications according to an embodiment of the present invention.

FIG. 15 is a plan view of a moving plate for high head applications according to an embodiment of the present invention.

FIG. 16 is a plan view illustrating the development of a moving plate for low head applications according to an embodiment of the present invention.

FIG. 17 is a plan view of a moving plate for low head applications with material reductions included according to an embodiment of the present invention.

FIG. 18 is a plan view illustrating the development of an upstream stationary plate for plate changer applications according to an embodiment of the present invention.

FIG. 19 is a plan view of an upstream stationary plate for plate changer applications according to an embodiment of the present invention.

FIG. 20 is a plan view of an upstream stationary plate for plate changer applications with a radiused entrance end according to an embodiment of the present invention.

The foregoing summary, as well as the following detailed description of certain embodiments, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings, certain embodiments. It should be understood, however, that the present invention is not limited to the arrangements and instrumentalities shown in the attached drawings.

The following reference characters are used in the specification and figures:

1. High head common plate 2. Long sides 3. Short side shutoff end 4. Short side orifice end 5. Longitudinal centerline 6. Orifice 7. Transverse orifice centerline 8. Transverse shutoff centerline 9. Shutoff position 10. Low head common plate 11. High head symmetrical plate 12. Shutoff margin circle 13. First transverse construction line 14. Second transverse construction line 15. Shutoff end construction line 16. Shutoff end truncation lines 17. First longitudinal construction lines 18. Second longitudinal construction lines 19. Orifice end construction lines 20. Third transverse construction line 21. Material reduction truncation lines 22. Orifice end truncation lines 23. Shutoff end truncated corners 24. Orifice end truncated corners 25. Corner radii 26. Truncated sides 27. Radiused shutoff end 28. Orifice margin circle 29. Low head symmetrical plate 30. High head moving plate 31. Entrance end 32. Exit end 33. Entrance end margin circle 34. Entrance end truncation lines 35. Exit end construction lines 36. Exit end truncation lines 37. Entrance end truncated corners 38. Exit end truncated corners 39. Radiused entrance end 40. Vessel shell 41. Vessel lining 42. Well nozzle 43. Mounting plate 44. Upstream stationary plate 45. Upstream plate fixed clamp 46. Upstream plate moveable clamp 47. Moving plate 48. Moving plate drive frame 49. Moving plate clamp 50. Downstream stationary plate 51. Downstream plate fixed clamp 52. Downstream plate moveable clamp 53. Moving plate clamp screw 54. Upstream stationary plate for tube changer 55. Orifice (of upstream stationary plate 44) 56. Orifice (of moving plate 47) 57. Orifice (of downstream stationary plate 50) 58. Pouring tube 59. Valve main frame 60. Low head moving plate 61. Stationary upstream plate 62. Well 63. Well nozzle flow channel 64. Pouring tube bore 65. Downstream face of downstream stationary plate 66. Fixed plate clamp screw 67. Three plate reciprocating valve 68. Opening (of well 62) 69. Opening (of valve main frame 59) 70. Symmetrical end 71. Preliminary plate 72. Side surfaces (of high head common plate 1) 73. Preliminary plate 74. Preliminary plate 75. Preliminary plate

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described more fully with reference to the accompanying drawings, in which several embodiments are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth here. Rather, these certain embodiments are examples of the invention, which has the full scope indicated by the language of the claims. Like numbers refer to like elements throughout. Furthermore, for purposes of explanation, numbers expressed in both terms of the number and through the use of “′” with the number may be referred to as primary and secondary, respectively. Additionally, while dimensions are provided herein, it is understood that those dimensions may be subject to at least acceptable tolerances, such as, for example, plus or minus 0.075 maximum design orifice diameters, and all angles that fall within the angle formed when the linear tolerances are applied to the construction.

FIG. 1 is a longitudinal section of a three plate reciprocating valve 67 with a changeable pour tube 58 and the plate clamping, or driving, components according to an embodiment of the present invention. As shown, the three plate reciprocating valve 67 includes an upstream stationary plate 44, a moving plate 47, and a downstream stationary plate 50. The three plate reciprocating valve 67 may be mechanically secured to a vessel shell 40 by a mounting plate 43, such as, for example, by mechanical fasteners, including a bolt(s), pin(s), and/or screw(s), among others. The vessel shell 40 may contain a vessel lining 41 that incorporates a well 62 that contains molten metal. The well 62 may have an opening 68 that is in communication with a well nozzle flow channel 63. The upstream stationary plate 44, moving plate 47, and downstream stationary plate 50 each have orifices 55, 56, 57, respectively, such that, when the moving plate 56 is fully in an open position, are generally aligned with the nozzle flow channel 63.

When the moving plate 47 is in the open position, and the orifices 55, 56, 57 are generally aligned; molten metal is free to flow at full capacity from the well 62, through the orifices 55, 56, 57 and into a pouring tube bore 64 of a pouring tube 58. When the moving plate 47 is in the partially closed position, as shown in FIG. 1, and the orifice 56 of the moving plate 47 is at least partially misaligned with the orifices 55, 57 of the upstream and downstream stationary plates 44, 50, molten metal may flow at a reduced rate. The valve system 67 is closed when misalignment between the orifice 56 of the moving plate 47 and the orifices of the upstream and downstream stationary plates 44, 50 prevents molten metal from flowing past the moving plate 47.

The moving plate 47 is held in a metal tight relationship between the upstream stationary and downstream stationary plates 44, 50, such as by a separate mechanical structure (not shown). Additionally, the moving plate 47 is driven between open and closed positions by a moving plate drive frame 48. The moving plate drive frame 48 contains a moving plate clamp 49 that provides compressive containment forces between the moving plate 47 and the moving plate drive frame 48.

The upstream stationary plate 44 is prevented from moving upstream by its contact with the mounting plate 43. The upstream stationary plate 44 is also compressively contained by an upstream plate fixed clamp 45 and an upstream movable clamp 46, which prevent the upstream stationary plate 44 from moving laterally with the moving plate 47 as the moving plate 47 is stroked between open and closed positions.

The downstream stationary plate 50 may be compressively contained by a downstream plate fixed clamp 51 and a downstream plate movable clamp 52 that prevent the downstream stationary plate 50 from moving laterally with the moving plate 47 as the moving plate 47 is stroked between open and closed positions. Additionally, the pouring tube 58 may be held in a metal tight relationship with a downstream face 65 of the downstream stationary plate 50, such as being held by a separate mechanical structure (not shown).

FIG. 2 is a view taken along line 2-2 of FIG. 1 illustrating an upstream face of the downstream stationary plate 50 and downstream plate fixed and movable clamps 51, 52. As shown, the downstream stationary plate 50 according to an embodiment of the present invention is clamped in a stationary state by the compressive containment of the downstream plate fixed and movable clamps 51, 52. As shown, the clamps 51, 52 contain inner surfaces that compliment, and mate with, the truncated shape of the downstream stationary plate 50. The downstream plate fixed clamp 51 may be anchored to a main frame 59. Additionally, the valve main frame 59 may provide a reaction point for a fixed plate clamp screw 66 and the downstream plate movable clamp 52. Moreover, actuation of the fixed plate clamp screw 66 may move the downstream plate moveable clamp 52 towards the downstream plate fixed clamp 51. When the downstream plate 52 is moved toward the downstream plate fixed clamp 51, compressive forces may be applied to a downstream stationary plate 50 that is positioned between the clamps 51, 52. Such compressive forces may be removed from the downstream stationary plate 50 by reversing the direction of the actuation of the fixed plate clamp screw 66 such that force exerted on the downstream plate moveable clamp 52 by the fixed plate clamp screw 66 is reduced or removed, and/or the movement of the fixed plate clamp screw 66 pulls the downstream plate moveable clamp 52 away from the downstream stationary plate 50.

FIG. 3 illustrates a top view of a moving plate 47 according to an embodiment of the present invention and a moving plate drive frame 48 encased within the valve main frame 59. As shown, the moving plate 47 is at least partially surrounded by the moving plate drive frame 48. The moving plate drive frame 48 contains a moving plate clamp 49 and a moving plate clamp screw 53. Actuation of the moving plate clamp screw 53 may force the moving plate clamp 49 toward the moving plate 47 such that the moving plate 47 is compressively contained between the moving plate clamp 49 and at least a portion of the moving plate drive frame 48. As shown, inner surfaces of the moving plate clamp 49 and a portion of the moving plate drive frame 48 may be configured to complement and mate at least a portion of the outer truncated surfaces of the moving plate 47. Also shown in FIG. 3 is a portion of the downstream plate movable clamp 52 and downstream of moving plate 47, which, according to certain embodiments, may also be encased inside the valve main frame 59.

FIGS. 4-9 illustrate for purposes of explanation the development and configurations of common plates 1, 10 according to embodiments of the present invention. More specifically, FIGS. 4-7 demonstrate the development and configuration of a high head common plate 1, while FIGS. 8 and 9 demonstrate the development and configuration of a low head common plate 10 according to embodiments of the present invention. FIGS. 7 and 9 illustrate embodiments of completed high and low head common plates 1, 10, respectively. The high head common plate 1 may be used in a variety of applications, such as applications involving ladles and high head pressures, among others, while the low head common plate 10 is configured for lower head pressure applications, such as, for example, a tundish system. Accordingly, as the high head common plate 1 is configured to withstand higher head pressures, or forces, the high head common plate may have a larger size and shape than the low head common plate 10.

The high and low head common plates 1, 10 may be used as an upstream stationary plate 44 and/or movable plate 47 in a two plate valve system, or as the upstream stationary plate 44, movable plate 47, and/or downstream stationary plate 50 in a three plate valve system. For example, in a two plate system, a first high head common plate 1 may be used as an upstream stationary plate 44, while a second high head common plate 1 may be used as a moving plate 47. According to such an embodiment, the upstream stationary high head common plate 1 may need to be rotated 180° degrees so that the orifices 6 of the both plates 44, 47 are misaligned when the moving plate 47 is in a closed position.

FIGS. 4 and 8 illustrate the development of the high and low head common plates 1, 10, respectively. For purposes of illustration and explanation, the development of the common plates 1, 10 is described herein as beginning with a preliminary plate 71 that has an orifice 6, long sides 2, 2′, a short side shutoff end 3, and a short side orifice end 4. Moreover, the common plates 1, 10 may be constructed without the use of such as a preliminary plate 71, such as, for example, through a molding or casting process, among others. The center of the orifice 6 is positioned along the longitudinal centerline 5 of the plate. Moreover, the center of the orifice 6 provides an intersection between the longitudinal centerline 5 and a transverse orifice centerline 7. According to certain embodiments, this intersection may provide a starting or reference point used in the development of the configuration of the high and low head common plates 1, 10. Additionally, the orifice 6 is configured to receive the passage of flowing molten metal through the common plate 1, 10.

The long sides 2, 2′ are positioned parallel to the longitudinal centerline 5. According to certain embodiments, the long sides 2, 2′ of the common plate 1, 10 are displaced away from the longitudinal centerline 5 at a distance that is equal to approximately 1.125 to 1.50 times the maximum diameter size the orifice 6 may have for an operative plate 1, 10, referred to as the maximum design orifice 6 diameter. More specifically, according to certain embodiments, the long sides 2, 2′ of the high head common plate 1 is displaced away from the longitudinal centerline 5 at a distance equal to approximately 1.375 to 1.50 times the maximum design orifice 6 diameter. Similarly, according to certain embodiments, the long sides 2, 2′ for the low head common plate 10 is displaced away from the longitudinal centerline 5 at a distance equal to approximately 1.125 to 1.25 times the maximum design orifice 6 diameter

The common plates 1, 10 also include a transverse shutoff centerline 8 positioned in proximity to the short side shutoff end 3 of the common plate 1, 10. When a common plate 1, 10 is used as a moving plate 47 and is in a closed position, the intersection of the transverse shutoff centerline 8 and the longitudinal centerline 5 may generally align with the centerline of the pouring orifice 9 of the valve system 67 and/or adjacent valve plate so as to prevent molten metal flowing through the moving closed plate 1, 10. Similarly, when a common plate 1, 10 is used as a stationary upstream or downstream plate 44, 50, the intersection of the transverse shutoff centerline 8 and the longitudinal centerline 5 may generally align with, or be in proximity to, the orifice 56 of the moving plate 47 when the moving plate is in a closed position. According to certain embodiments, the transverse shutoff centerline 8 may be positioned approximately 1.5 to 2.5 times the maximum design orifice 6 diameter away from the transverse orifice centerline 7. Additionally, the short side shutoff end 3 may be positioned at approximately 1.0 times the maximum design orifice 6 diameter beyond the transverse shutoff centerline 8.

According to certain embodiments, the short side orifice end 4 is configured to be approximately 1.625 to 2.0 times the maximum design orifice 6 diameter away from the transverse orifice centerline 7. More specifically, for certain embodiments of the high head common plate 1, the short side orifice end 4 is configured to be approximately 1.75 to 2.0 times the maximum design orifice 6 diameter away from the transverse orifice centerline 7. Similarly, according to certain embodiments of the low head common plate 10, the short side orifice end 4 may be positioned approximately 1.625 to 1.75 times the maximum design orifice 6 diameter from the transverse orifice centerline 7.

The common plate 1, 10 also includes a shutoff margin circle 12. When used as a moveable plate, the shutoff margin circle 12 provides a sufficient area to prevent the flow of molten metal through an adjacent orifice, such as the orifice 55 of an upstream stationary plate 44 around the common plate 1, 10. According to certain embodiments, the shutoff margin circle 12 has a diameter that is approximately 2.0 times the maximum design orifice 6 diameter, and is positioned at the intersection of the longitudinal centerline 5 and the transverse shutoff centerline 8.

The size and shape of the common plate 1, 10 may be further defined by locating truncation lines. For example, a first transverse construction line 13 is positioned inside the short side office end 5. More specifically, according to certain embodiments, the first transverse construction line 13 may be positioned approximately 1.0 to 1.5 times the maximum design orifice 6 diameter inside the short side orifice end 4. According to embodiments of the low head common plate 10, the first transverse construction line 13 may be positioned at approximately 1.0 to 1.25 times the maximum design orifice 6 diameter inside the short side orifice end 4. A second transverse construction line 14 for the common plate 1, 10 may be positioned at approximately 0.5 times the maximum design orifice 6 diameter from the first transverse construction line 13 in the direction of the short side orifice end 4, while a third transverse construction line 20 may be positioned approximately 0.25 times the maximum design orifice 6 diameter from the transverse orifice centerline 7 toward the transverse shutoff centerline 8.

The development of the common plates 1, 10 may also include locating a pair of first longitudinal construction lines 17, 17′. According to certain embodiments, the first longitudinal construction lines 17, 17′ may be generally parallel to the long sides 2, 2′ and be positioned at approximately 0.25 times the maximum design orifice 6 diameter inside the long sides 2, 2′. According to certain embodiments, the development of the high head common plate 1 may also include locating second longitudinal construction lines 18, 18′ that are parallel to the longitudinal construction lines 17, 17′ and positioned at approximately 0.5 times the maximum design orifice 6 diameter inside of the long sides 2, 2′.

As shown in FIGS. 4 and 8, the development of the common plates 1, 10 also includes positioning a pair of shutoff end truncation lines 16, 16′ that are tangent to the shutoff margin circle 12. The shutoff end truncation lines 16, 16′ extend from the intersection of the transverse shutoff centerline 8 and the long sides 2, 2′ until they intersect with the short side shutoff 3.

The development of the common plates 1, 10 may also include locating orifice end construction lines 19, 19′ around the short side orifice end 4 of the preliminary plate 71. With respect to the high head common plate 1, the orifice end construction lines 19, 19′ may extend from the intersection of the longitudinal centerline 5 and the first transverse construction line 13 to the intersection of second transverse construction line 14 and the second longitudinal construction lines 18, 18′. For the low head common plate, the orifice end construction lines 19, 19′ may extend from the intersection of the longitudinal centerline 5 and the first transverse construction line 13 to the intersection of second transverse construction line 14 and the first longitudinal construction lines 17, 17′.

The configuration of the common plate 1, 10 also includes locating orifice end truncation lines 22, 22′. The orifice end truncation lines 22, 22′ may be perpendicular to orifice end construction lines 19, 19′, and extend from the intersection of the second transverse construction line 14 and long sides 2, 2′ until they intersect the short side orifice end 4. Additionally, material reduction truncation lines 21, 21′ are positioned at the short side shutoff end 3, and also provide boundaries for truncation of material from the preliminary plate 71. For example, as shown in FIGS. 4 and 5, with respect to embodiments of the high head common plate 1, the material reduction truncation lines 21, 21′ extend from the intersection of the third transverse construction line 20 and the long sides 2, 2′ to the nearest intersection of the short side shutoff end 3 and the first longitudinal construction lines 17, 17′. As shown in FIG. 8, with respect to the low head common plate 10, the material reduction truncation lines 21, 21′ are tangent to the shutoff margin circle 12 and extend from the intersections of third transverse construction line 20 and the long sides 2, 2′ until the material reduction truncation lines 21, 21′ intersect the short side shutoff end 3.

At least FIGS. 5 and 6 illustrate illustrates continued formation of the configuration of the high head common plate 1 in which FIG. 4 has been modified by truncations at the shutoff end truncation lines 16, 16′ and orifice end truncation lines 22, 22′. Moreover, as seen in FIG. 5, the shutoff end truncation lines 16, 16′ and orifice end truncation lines 22, 22′ have been replaced by shutoff end truncated corners 23, 23′ and orifice end truncated corners 24, 24′, respectively. FIG. 6 illustrates further truncation of the high head common plate 1. More specifically, a portion of the long sides 2, 2′ have been truncated along material truncation sides 26, 26′. Similar truncations for the low head common plate 10 are shown in FIG. 9. Additionally, according to certain embodiments of both the high and low head common plates 1, 10, the external corners of these truncated corners 23, 23′ and corners 24, 24′ may transition to at their respective unions with the long sides 2, 2, short side shutoff end 3, and/or short side orifice end 4 with a corner radii 25 rather than a sharp corner.

FIGS. 7 and 9 illustrate the completed configuration of high and low head common plates 1, 10, respectively, according to embodiments of the present invention. As shown, according to certain embodiments, the common plates 1, 10 include an orifice 6, a short side shutoff end 3, a short side end 4, truncation sides 26, 26′, and long sides 2, 2′. According to certain embodiments, the short side end 4 includes orifice end truncation corners 24, 24′. The short side shut off end 3 may also include shutoff truncated corners 23, 23′. Further, as shown in FIG. 9, the short side shut off end 3 may also include a raduised shutoff end 27 that follows the shutoff margin circle 12 from the tangency of a first shutoff end truncated corners 23 to the tangency of the second shutoff end truncated corner 23′.

The mating surfaces used to contain the common plate 1, 10 in a valve system 67 may be configured to compliment the orifice end truncation corners 24, 24′, truncation sides 26, 26′, shutoff truncated corners 23, 23′, and/or raduised shutoff end 27. For example, according to embodiments in which the common plate 1, 10 is used as a downstream stationary plate 50, the downstream plate fixed or movable clamp 51, 52 may be configured to have complimentary surfaces that mate at least portion of the orifice end truncation corners 24, 24′ of the common plate 1, 10. Additionally, the truncated configurations of the high head and low head common plates 1, 10 reduce the size and weight of the plates 1, 10. Such reductions in size and weight allows for a reduction in the size and weight of the corresponding support structures for the plates 1, 10 in the valve system and any associated drivers used to move the positioning of the plates 1, 10 in the system 67.

Further, when assembled in a gate valve system 67, the common plates 1, 10 are configured to withstand compressive forces so as to reduce the formation of stress fractures commonly found in upstream stationary, movable, and/or downstream stationary plates 44, 47, 50. Such stress typically form from temperature differences across the plates 44, 47, 50, namely temperature differences between the areas of the plates 44, 47, 50 that are in the vicinity of the orifices 55, 56, 57 were molten metal is flowing and the cooler outer edges of the plates 44, 47, 50. The common plate 1, 10 of the present invention is configured for application of such compressive forces across the common plate 1, 10 while also providing functionality sufficient for use in gates valve systems 67 used in high or low pressure metal pouring applications. Moreover, the truncated corners 23, 23′ of the common plate 1, 10 vector the compressive or clamping forces, as discussed above with respect to FIGS. 2 and 3, to resist cracking in the common plate 1, that typically occurs as a result of temperature differences across the plate. By placing the common plate 1, 10 in a compressively stressed state, such vectoring of compressive forces improves the ability of the common plate 1, 10 will resist tensile stresses that are induced at the cooler outside portion of the plate 1, 10. Moreover, the configurations of the present invention improve the ability of the common plate 1, 10 to counteract such stress, which results in the formation of fewer, and less severe propagation, of cracks that start at the outside of the common plate 1, 10.

FIGS. 10 and 11 and FIGS. 12 and 13 illustrate the development and configuration of a high head symmetrical plate 11 and low head symmetrical plate 29, respectively, according to embodiments of the present invention. Further, FIG. 11 illustrates a completed high head symmetrical plate 11, while FIG. 13 illustrates a completed low head symmetrical plate 29. The symmetrical plates 11, 29 include an orifice 6, which divides two generally symmetrical ends 70, 70′ of the symmetrical plates 11, 29. When a symmetrical plate 11, 29 is used as a moving plate 47, the symmetrical ends 70, 70′ may provide two separate areas that may be moved into position beneath the pouring orifice of the valve gate system 67 so as to stop the flow of molten through the system 67. According to certain embodiments, a first symmetrical end 70 may be used to stop such flow of molten metal until that symmetrical end 70 becomes too worn or compromised to continue to be used, after which the second symmetrical end 70′ may be used to shutoff the flow of molten metal. Alternatively, the use of the first and second symmetrical ends 70, 70′ to shutoff the flow of molten metal in the valve system 67 may be regularly or irregularly alternated.

Again, for purposes of illustration and explanation, the development of the symmetrical plates 11, 29 may begin with a preliminary plate 73 that includes an orifice 6. Again, the orifice 6 is configured to allow molten metal to flow through the plate 11, 29 when the plate 11, 29 is properly aligned in the gate valve system 67. The orifice 6 of the symmetrical plate 11, 29 may be positioned at the intersection of a longitudinal centerline 5 and a transverse orifice centerline 7. As shown in at least FIGS. 10 and 12, the preliminary plate 73 may include long sides 2, 2′ that are parallel to the longitudinal centerline 5. According to certain embodiments, the long sides 2, 2′ may be approximately 1.125 to 1.50 times the maximum design orifice 6 diameter away from the longitudinal centerline 5. More specifically, for high head applications, the long sides 2, 2′ of the symmetrical plate 11 may be positioned approximately 1.375 to 1.50 times the maximum design orifice 6 diameter away from the longitudinal centerline 5. Similarly, for low head applications, the long sides 2, 2′ are approximately 1.125 to 1.25 times the maximum design orifice 6 diameter away from longitudinal centerline.

The preliminary plate 73 also includes a transverse shutoff centerline 8 that is positioned at a shutoff position 9 on both symmetrical ends 70, 70′. A shutoff position 9 is generally aligned with the pouring orifice of the gate valve system 67 when the symmetrical plate 11, 29 is a moving plate 47 that is in a closed position. According to certain embodiments, the shutoff position 9 may be located at approximately 1.50 to 2.50 times the maximum design orifice 6 diameter away from the transverse orifice centerline 7.

The symmetrical plate 11, 29 may also include at least a pair of shutoff margin circles 12, 12′ that provide sufficient area to assist in preventing continued downstream flow of molten metal from adjacent orifice, such as the orifice 55 of an upstream stationary plate 44. The shutoff margin circles 12, 12′ are positioned at the intersection of the longitudinal centerline 5 and the transverse shutoff centerlines 8, 8′. Additionally, according to certain embodiments, the shutoff margin circles 12, 12′ have a diameter that is approximately two times the maximum design orifice 6 diameter.

As shown in FIGS. 10 and 12, the development of the symmetrical plates 11, 29 includes locating first transverse construction lines 13, 13′, shutoff truncation lines 16, 16′, 16″, 16′″, first longitudinal construction lines 17, 17′, and material reduction truncation lines 21, 21′, 21″, 21′″. The first transverse construction lines 13, 13′ may be positioned at a location that is approximately 0.25 times the maximum design orifice 6 diameter from either side of the transverse orifice centerline 7. The shutoff end truncation lines 16, 16′, 16″, 16′″ may be tangent to the shutoff margin circles 12,12′, and extend from the intersection of the transverse shutoff centerline 8, 8′ and the long sides 2, 2′ until the shutoff end truncation lines 16, 16′, 16″, 16′″ intersect with the short side shutoff end 3, 3′. The first longitudinal construction lines 17, 17′ may be positioned at approximately 0.25 times the maximum design orifice 6 diameter inside of long sides 2, 2′. Additionally, as shown, material reduction truncation lines 21, 21′, 21″, 21′″ extend from the intersection of the long sides 2, 2′ and the first transverse construction lines 13, 13′ to the intersection of the short side shutoff end 3, 3′ and the first longitudinal construction lines 17, 17′.

FIGS. 11 and 13 illustrated the completed high and low head symmetrical plates 11, 29, respectively, after material reductions. For example, as shown, material reductions to the long sides 2, 2′ are provide by material reductions along truncated sides 26, 26′, 26″, 26′″. These reductions extend to the corners of the symmetrical plates 11, 29 where they transition from corner radii 25 to shutoff end truncated corners 23, 23′, 23″, 23′″. Accordingly, as shown, the completed symmetrical plates 11, 29 include an orifice 6, with the orifice generally separating symmetrical ends 70, 70′ of the symmetrical plates 11. Each symmetrical end 70, 70′ may be generally defined by truncated sides 26, 26′, 26′″, 26″″ that transition into shutoff end truncated corners 23, 23′, 23″, 23′″ and the remaining shut off ends 3, 3′.

FIGS. 14 and 15 illustrate the development and configuration of a high head moving plate 30 according to an embodiment of the present invention. FIGS. 16 and 17 illustrate the development of a low head moving plate 60 according to an embodiment of the invention. The completed high and low head moving plates 30, 60 are illustrated in FIGS. 15 and 17, respectively. Again, for purposes of illustration and explanation, the moving plates 30, 60 may begin with a preliminary plate 74 having an orifice, long sides 2, 2′, a short side shutoff end 3, and a short side orifice end 4. The orifice 6 is located at the intersection of a longitudinal centerline 5 and a transverse orifice centerline 7. According to certain embodiments, the long sides 2, 2′ are parallel to the longitudinal centerline 7 and offset away from the longitudinal centerline 7 at a distance that is approximately 1.50 to 1.75 times the maximum design orifice 6 diameter. More specifically, according to certain embodiments for the high head moving plate 30, the long sides 2, 2′ are offset from the longitudinal centerline 7 by a distance that is located approximately 1.75 times the maximum design orifice 6 diameter. With respect to the low head moving plate 60, according to certain embodiments, the long sides 2, 2′ are offset from the longitudinal centerline 7 by a distance that is located approximately 1.50 times the maximum design orifice 6 diameter.

The moving plates 30, 60 also include a transverse shutoff centerline 8 that is located at a shutoff position 9. The shutoff position 9, which is shown as a phantom circle, indicates the location of the orifices of the upstream and downstream stationary plates 44, 50 when the moving plate 30, 60 is in a closed position. Moreover, the shutoff position is located the shutoff stroke distance away from the center of the pouring orifice 6. Moreover, the shutoff position may be located at the intersection of the longitudinal centerline 5 and the transverse shutoff centerline 8. According to certain embodiments, the transverse shutoff centerline 8, which may be perpendicular to the longitudinal centerline 5, is located approximately 1.5 to 2.5 times the maximum design orifice 6 diameter from transverse orifice centerline 7.

The short side orifice end 4 of the moving plates 30, 60 is located approximately 1.25 to 1.375 times the maximum design orifice 6 diameter beyond the transverse orifice centerline 7. For example, with respect to the high head moving plate 30, the short side orifice end 4 may be located approximately 1.375 times the maximum design orifice 6 diameter beyond the transverse orifice centerline 7. Additionally, according to certain embodiments, the low head moving plate 60 includes a short side orifice end 4 that is located approximately 1.25 times the maximum design orifice 6 diameter beyond the transverse shutoff centerline 8.

With respect to the short side shutoff end 3, according to certain embodiments, the short side shutoff end 3 is located approximately 1.75 to 2.125 times the maximum design orifice 6 diameter beyond the transverse orifice centerline 7. For example, with respect to the high head moving plate 30, the short side shutoff end 3 may be located approximately 2.125 times the maximum design orifice 6 diameter beyond the transverse shutoff centerline 8. Additionally, according to certain embodiments, the low head moving plate 60 includes a short side shutoff end 3 that is located approximately 1.75 to 1.875 times the maximum design orifice 6 diameter beyond the transverse shutoff centerline 8.

The development of the moving plate 30, 60 also includes configuring a margin circle 28 that is sized and positioned to prevent the downstream flow of molten metal from an adjacent upstream orifice with the moving plate 30, 60 is in a closed position. The center of the margin circle 28 may be positioned at the intersection of the longitudinal centerline 5 and the transverse orifice centerline 7. According to certain embodiments, the margin circle 28 has a diameter that is approximately 2.50 to 2.75 times the maximum design orifice 6 diameter. For example, according to embodiments for a high head moving plate, the margin circle 28 has a diameter that is approximately 2.75 times the maximum design orifice 6 diameter. Additionally, for certain embodiments of the low head moving plate 60, the orifice margin circle 28 has a diameter that is approximately 2.50 times the maximum design orifice 6 diameter.

As shown in FIGS. 15 and 17, the moving plate 30, 60 also includes a first transverse construction line 13 that is approximately 0.5 to 1.0 times the maximum design orifice 6 diameter inside of the short side orifice end 4. For example, according to certain embodiments of the high head moving plate 30, the first transverse construction line 13 is positioned 1.0 times the maximum design orifice 6 diameter inside of the short side orifice end 4. Additionally, according to certain embodiments of the low head moving plate 60, the first transverse construction line 13 is positioned 0.5 times the maximum design orifice 6 diameter inside of the short side orifice end 4.

As also shown in FIGS. 15 and 17, the moving plate 30, 60 also includes a second transverse construction line 14 approximately 0.375 to 0.5 times the maximum design orifice 6 diameter away from the transverse shutoff centerline 8 toward the short side shutoff end 3. For example, according to certain embodiments of the high head moving plate 30, the second transverse construction line 14 is located approximately 0.5 times the maximum design orifice 6 diameter beyond, and parallel to, the transverse shutoff centerline 8. Additionally, according to certain embodiments of the low head moving plate 60, the second transverse construction line 14 is located approximately 0.375 times the maximum design orifice 6 diameter beyond, and parallel to, the transverse shutoff centerline 8.

The development of the moving plate 30, 60 further includes positioning a third transverse construction line 20 approximately 1.125 to 1.50 times the maximum design orifice 6 diameter away from the transverse shutoff centerline 8 toward the short side shutoff end 3. For example, according to embodiments in which moving plate is a high head moving plate 30, the third transverse construction line 20 is approximately 1.50 times the maximum design orifice 6 diameter beyond, and parallel to, the transverse shutoff centerline 8. Additionally, according to embodiments in which moving plate is a low head moving plate 60, the third transverse construction line 20 is approximately 1.0 to 1.125 times the maximum design orifice 6 diameter beyond, and parallel to, the transverse shutoff centerline 8.

As shown in FIGS. 14 and 16, the development of the moving plate 30, 60 may also include locating orifice end truncation lines 22, 22′. The orifice end truncation lines 22, 22′ extend from the intersection of long sides 2, 2′ and the first transverse construction line 13 to tangencies with the orifice margin circle 28 until the orifice end truncation lines 22, 22′ intersect with the short side orifice end 4. Additionally, shutoff end construction lines 15, 15′ extend from the intersection of the longitudinal centerline 5 and the second transverse construction line 14 to the intersection of longitudinal construction lines 17, 17′ and third transverse construction line 20. Further, shutoff end truncation lines 16, 16′ are configured perpendicular to shutoff end construction lines 15, 15′ and extend from the intersection of the long sides 2, 2′ and the transverse construction line 20 until they intersect short side shutoff end 3.

The moving plates 30, 60 also include material reduction truncation lines 21, 21′ that are positioned to provide a portion of the outer boundaries the moving plates 30, 60. For example, according to certain embodiments of the low head moving plate 60, material reduction truncation lines 21, 21′ extend from the intersections of the long sides 2, 2′ and the transverse shutoff centerline 8 to the intersections of the longitudinal construction lines 17, 17′ and the first transverse construction line 13. With regard to embodiments of the high head moving plate 30, material reduction truncation lines 21, 21′ extend from the intersections of the long sides 2, 2′ and the transverse shutoff centerline 8 to the intersections of the longitudinal construction lines 17, 17′ and the short side orifice end 4.

As shown in FIGS. 15 and 17, according to certain embodiments, completion of the high and low head moving plates 30, 60 may include truncating material from the long sides 2, 2′ along reduction truncation lines 21, 21′ to form material reduction sides 26, 26′ of the moving plates 30, 60, as well as truncating material along the shutoff end truncated corners 23, 23′ and orifice end truncated corners 24, 24′. Further, rather than having sharp corners, the outer boundaries of the moving plates 30, 60 may incorporate corner radii 25 in the transition to the truncated portions 23, 23′, 24, 24′, 26, 26′.

FIGS. 18 to 20 illustrate the development and configuration of a stationary upstream plate 61 for a plate changing valve according to an embodiment of the present invention. A plate changing valve has the ability to exchange a plate downstream of the upstream stationary plate while metal is flowing. Again, for purposes of illustration and explanation, the stationary upstream plate 61 may begin with a preliminary plate 75 that has an orifice 6, long sides 2, 2′, an entrance end 31, and an exit end 32. The orifice 6 is located at the intersection of a longitudinal centerline 5 and a transverse orifice centerline 7. According to certain embodiments, the long sides 2, 2′ are located parallel to the longitudinal centerline 5 at a distance approximately 1.125 to 1.25 times the maximum design orifice 6 diameter. The entrance end 31 is configured to extend over the leading edge of the incoming exchangeable plate. According to certain embodiments, the entrance end 31 is located approximately 1.625 to 1.875 times the maximum design orifice 6 diameter from transverse orifice centerline 7. Further, the exit end 32 is configured to cover almost all of the exchangeable in the operating position. More specifically, truncations of the exit end 32 in accordance with embodiments of the present invention effectively move the exit end 32 of the upstream plate 61 tending to expose a portion of the sealing face of the adjacent exchangeable plate. The length of the exit end 32 is configured to minimize and/or eliminate such exposure. Further, the truncations are configured so as to vector clamping forces to resist cracking in the upstream plate 61. According to embodiments, the exit end 32 is located approximately 1.50 to 1.625 times the maximum design orifice 6 diameter away from the transverse orifice centerline 7 on the side of transverse orifice centerline 7 opposite that of the entrance end 31.

The upstream plate 61 includes a first transverse construction line 13 that is positioned at approximately 1.0 times the maximum design orifice 6 diameter inside the entrance end 31. A second transverse construction line 14 may also be located approximately 1.0 to 1.25 times the maximum design orifice 6 diameter inside the exit end 32. Additionally, a third transverse construction line 20 is located approximately 0.5 times the maximum design orifice 6 diameter from second transverse construction line 14 toward the exit end 32. These lines 13, 14, 20 assist in locating the start or ending points of truncation lines that generally define a portion of the shape of the upstream plate 61, as shown below.

As illustrated in FIGS. 18 to 20, first longitudinal construction lines 17, 17′ are located 0.25 times the maximum design orifice 6 diameter inside of long sides 2, 2′. The upstream plate 61 also includes an entrance end margin circle 33 that is configured to provide a radiused entrance end 39 and may be used in defining the shape of the mating surface of the clamp that at least partially secures the position of the stationary upstream plate 61 in a valve system. According to certain embodiments, the entrance end margin circle 33 has a diameter that is approximately 2.0 times the maximum design orifice 6 diameter and is centered at the intersection of the longitudinal centerline 5 and first transverse construction line 13.

Entrance end truncation lines 34, 34′ are configured to generally identify a portion of the boundaries of the upstream plate 61, or boundaries where material may be truncated from the preliminary plate 75. The end truncation lines 34, 34′ are tangent to entrance end margin circle 33 and extend from the intersections of the long sides 2, 2′ and first transverse construction line 13 until the end truncation lines 34, 34′ intersect with entrance end 31.

Exit end truncation lines 36, 36′ also generally identify a portion of the boundaries of the upstream plate 61, or boundaries where material may be truncated from the preliminary plate 75. The exit end construction lines 35, 35′ extend from the intersection of the longitudinal centerline 5 and the second transverse construction line 14 to the intersections of third transverse construction line 20 and first longitudinal construction lines 17, 17′. Exit end truncation lines 36, 36′ extend from the intersections of third transverse construction line 20 and the long sides 2, 2′, are perpendicular to exit end construction lines 35, 35′, and continue until they intersect exit end 32. The removal of material along the exit end truncation lines 36, 36′ provide first and second exit end truncated corners 38, 38′ along an outer boundary of the plate 61.

Referring to FIG. 19 completion of a stationary upstream plate 61 involves generating entrance end truncated corners 37, 37 and exit end truncated corners 38, 38′. Additionally, corner radii 25 may be positioned at all external corners. Additionally, FIG. 20 illustrates a completed stationary upstream plate 61. As shown, the stationary upstream plate 61 includes a radiused entrance end 39 that follows the entrance end margin circle 33 from the tangency with entrance end truncated corner 37 to the tangency with the other entrance end truncated corner 37′. 

What is claimed:
 1. An improved common valve plate for controlling a flow of molten metal in a slide gate valve comprising: a refractory plate having an orifice, a first and second long side, a first and second orifice end truncated corners, a first and second shutoff end truncated corners, a shutoff end, a short side orifice end, a shut off margin circle, and a longitudinal centerline, in which: (i) the orifice is configured to allow molten metal to flow through the refractory plate, the center of the orifice being positioned at the intersection of the longitudinal centerline and a transverse orifice centerline; (ii) the first and second long sides being parallel to the longitudinal centerline, the first and second long sides being positioned at opposite sides of the longitudinal centerline at a distance of approximately 1.125 to 1.50 times the maximum design orifice diameter; (iii) the short side shutoff end is approximately 1.0 times the maximum design orifice beyond a transverse shutoff centerline, the transverse shutoff centerline being perpendicular to the longitudinal centerline and positioned approximately 1.5 to 2.5 times the maximum design orifice diameter from the transverse orifice centerline; (iv) the short side orifice end is located at an end of the refractory plate opposite of that of the short side shutoff end, the short side orifice end being approximately 1.625 to 2.0 times the maximum design orifice away from the transverse orifice centerline at an end of the refractory plate opposite that of the short side shutoff end, the distance between the short side shutoff end and short orifice end being the sum of the shut off stroke plus the distance from the transverse orifice centerline to the short side orifice end plus the distance from the transverse centerline at shutoff to the shutoff end; (v) the shutoff margin circle providing an area sufficient to prevent molten metal from an upstream orifice that is adjacent to the refractory plate from flowing around the first and second sides or truncated sides, the shutoff margin circle being centered at the intersection of the longitudinal centerline and transverse shutoff centerline and having a diameter that is approximately 2.0 times the maximum design orifice diameter; (vi) the first and second shutoff truncate corners being positioned at the shutoff end of the refractory plate, the first truncated shutoff corner being defined by a first line that extends from the intersection of the first long side and the transverse shutoff centerline falls tangent to the shutoff margin circle and continues until the first line intersects the short side shutoff end, the second truncated shutoff corner being defined by a second line that extends from the intersection of the second long side and the transverse shutoff centerline falls tangent to the shutoff margin circle and continues until the second line intersects the short side shutoff end; and (vii) the first and second orifice end truncated corners being positioned at the orifice end of the refractory plate, the first and second orifice end truncated corners extending from the intersection of the first and second long sides, respectively, and a second transverse construction line until intersecting the short side orifice end, the first short end truncated corner being perpendicular to a first orifice end construction line, the second short end truncated corner being perpendicular to a second orifice end construction line, in which: the second transverse construction line is approximately 0.5 times the maximum design orifice diameter away from a first transverse construction line that is approximately 1.0 to 1.5 times the maximum design orifice diameters inside the short side orifice end, the first orifice end construction line extends from the intersection of the longitudinal centerline and the first transverse construction line and through the intersection of the second transverse construction line and a first primary longitudinal construction line, the first primary longitudinal construction line being approximately 0.25 to 0.5 times the maximum design orifice diameter inside the first long side; and the second orifice end construction line extends from the intersection of the longitudinal centerline and the first transverse construction line and through the intersection of the second transverse construction line and a first secondary longitudinal construction line, the first secondary longitudinal construction line being approximately 0.25 to 0.5 times the maximum design orifice diameter inside the second long side.
 2. The common valve plate of claim 1, further including a first and a second truncated side, wherein the first truncated side extends from the intersection of the first long side and a third transverse construction line to the intersection of the first primary longitudinal construction line and the short side shutoff end, and the second side extends from the intersection of the second long side and the third transverse construction line to the intersection of the first secondary longitudinal construction line and the short side shutoff end, wherein the third transverse construction line is positioned approximately 0.25 times the maximum design orifice diameter from the transverse orifice centerline toward the transverse shutoff centerline.
 3. The common valve plate of claim 1, wherein the first and second truncation sides extend from (a) the intersection of the first and second long sides, respectively, and a line that is approximately 0.25 times the maximum design orifice diameter beyond the transverse orifice centerline in the direction of the short side shutoff end to (b) the short side shutoff end, and are tangent to a circle that is centered the intersection of the longitudinal centerline and the transverse shutoff centerline and is approximately 2.0 times the maximum design orifice diameter.
 4. The common valve plate of any one of claims 1-3, wherein each of the first and second sides are positioned at opposite sides of the longitudinal centerline at a distance of approximately 1.375 to 1.50 times the maximum design orifice diameter.
 5. The common valve plate of any one of claims 1-4, wherein the short side orifice end is approximately 1.75 to 2.0 times the maximum design orifice away from the transverse orifice centerline.
 6. The common valve plate of any one of claims 1-5, wherein the first orifice end construction line is approximately 0.5 times the maximum diameter inside the first long side and the second orifice end construction line is approximately 0.5 times the maximum diameter inside the second long side.
 7. The common valve plate of any one of claims 1-3, wherein each of the first and second sides are positioned at opposite sides of the longitudinal centerline at a distance of approximately 1.125 to 1.25 times the maximum design orifice diameter.
 8. The common valve plate of any one of claim 1-3 or 7, wherein the short side orifice end is approximately 1.625 to 1.75 times the maximum design orifice away from the transverse orifice centerline.
 9. The common valve plate of anyone of claims 1-3 and 7-8, wherein the first orifice end construction line is approximately 0.25 times the maximum diameter inside the first long side and the second orifice end construction line is approximately 0.25 times the maximum diameter inside the second long side.
 10. The common valve plate of any one of claims 1-9, wherein the external corners of the refractory plate are radiused.
 11. The common valve plate of any one of claims 1-10, wherein the plate is partially encased in a metal can.
 12. The common valve plate of any one of claims 1-11, wherein the plate is encircled by a metal band.
 13. The common valve plate of any one of claims 1-12, wherein the shutoff end of the refractory plate is defined by a radius that is 1.0 times the maximum design orifice diameter and which is tangent to the first and second short end truncated corners and the short side shutoff end.
 14. The common valve plate of any one of claims 1-13, wherein the shutoff end of the refractory plate is a radiused shutoff end that follows the shutoff margin circle from the tangency of the first shutoff end truncated corner to the second shutoff truncated corner.
 15. The common valve plate of any one of claims 1-14, wherein the refractory plate is made asymmetrical about the longitudinal centerline by displacing one of the orifice end truncations plus or minus 0.125 to 0.25 maximum design orifice diameters along the long side.
 16. The common valve plate of any one of claims 1-15 wherein the refractory plate includes external corners that are radiused.
 17. An improved symmetrical valve plate for controlling a flow of molten metal in a slide gate valve, comprising: a refractory plate having an orifice, a longitudinal centerline, a transverse orifice centerline, a first and a second symmetrical end, a first and second long side, in which: (i) the transverse shutoff centerlines positioned along said longitudinal centerline at a distance of the shutoff stroke from the transverse centerline at the orifice on either side of said centerline at orifice; (ii) the first and second long sides being located on opposite sides of the longitudinal centerline, the first and second long sides being positioned approximately 1.125 to 1.50 times the maximum design orifice diameter away from the longitudinal centerline; and (iii) the first and second symmetrical ends of the refractory plate being divided generally at the transverse orifice centerline, the first and second symmetrical ends each configured to stop the flow of molten metal from an adjacent upstream orifice, the first and second symmetrical ends both having a first and second truncated side, a transverse shutoff centerline, and a short side cutoff end, in which: (a) the short side shutoff ends of the first and second symmetrical end being separated by a distance of equal to approximately twice the shutoff stroke plus 1.0 times the maximum design orifice diameter beyond the shutoff stroke on both ends; (b) the transverse shutoff centerline is positioned approximately 1.50 to 2.0 times the maximum design orifice from the transverse orifice centerline; and (c) for both the first and second side symmetrical ends, the first and second truncated sides are joined to short side shutoff end by truncated corners, the truncated corners being tangent to a circle having a diameter 2.0 times the maximum design orifice diameter that is located at the intersection of the longitudinal centerline and the transverse shutoff centerline, the truncated corners extending from the intersection of transverse shutoff centerlines and the first and the second long sides until the truncated sides intersect the short side shutoff ends.
 18. The symmetrical valve plate of claim 17, wherein the first and second long sides are positioned 1.375 to 1.50 times the maximum design orifice diameter away from the longitudinal centerline.
 19. The symmetrical valve plate of claim 17, wherein the first and second long sides are positioned 1.125 to 1.25 times the maximum design orifice diameter away from the longitudinal centerline.
 20. The symmetrical valve plate of claim 18 or 19, wherein the first and symmetrical ends both having first and second truncated sides, in which: (i) the first truncated side of the first symmetrical end is configured to extend from the intersection of a first primary transverse construction line and a first long side to the intersection of the first primary longitudinal construction line and the short side shutoff end of the first symmetrical end; (ii) the second truncated side of the first symmetrical end is configured to extend from the intersection of a first primary transverse construction line and a second long side to the intersection of the first secondary longitudinal construction line and the short side shutoff end of the first symmetrical end; (iii) the first truncated side of the second symmetrical end is configured to extend from the intersection of a first secondary transverse construction line and a first long side to the intersection of the first primary longitudinal construction line and the short side shutoff end of the second symmetrical end; (ii) the second truncated side of the second symmetrical end is configured to extend from the intersection of a first secondary transverse construction line and a second long side to the intersection of the first secondary longitudinal construction line and the short side shutoff end of the second symmetrical end; and (a) the first primary and secondary transverse construction lines are located at opposite sides of the transverse orifice centerline and are positioned approximately 0.25 times the maximum design orifice from the transverse orifice centerline; and (b) the first primary and secondary longitudinal construction lines are located on opposite sides of the longitudinal centerline and are positioned approximately 0.25 times the maximum design orifice from inward from the adjacent first and second long sides.
 21. The symmetrical valve plate of claim 20, wherein the external corners are radiused.
 22. The symmetrical valve plate of claim 20, wherein the plate is partially encased in a metal can.
 23. The symmetrical valve plate of claim 20, wherein the plate is encircled by a metal band.
 24. The symmetrical valve plate of claim 20, wherein both shutoff ends of the refractory plate are defined by a radius that is 1.0 times the maximum design orifice diameter and which is tangent to the first and second short end truncated corners and the short side shutoff end.
 25. The symmetrical valve plate of claim 15, wherein the plate is made asymmetrical about the longitudinal centerline by displacing one of the orifice truncations plus or minus 0.125 to 0.25 along the long side.
 26. An improved moving valve plate for controlling a flow of molten metal in a slide gate valve, comprising: a refractory valve plate having an orifice, a first and a second long side, a short side shutoff end, a short side orifice end, a first and a second shutoff end truncated corners, and a first and second orifice end truncated corners, in which: (i) the orifice is configured to allow molten metal to flow through the refractory plate, the center of the orifice being positioned at the intersection of the longitudinal centerline and a transverse orifice centerline; (ii) the first and second long sides being parallel to the longitudinal centerline, the first and second long sides being positioned at opposite sides of the longitudinal centerline at a distance of approximately 1.50 to 1.75 times the maximum design orifice diameter; (iii) the short side orifice end is approximately 1.25 to 1.375 times the maximum design orifice beyond a transverse orifice centerline. the transverse shutoff centerline being perpendicular to the longitudinal centerline and positioned approximately 1.5 to 2.5 times the maximum design orifice diameter from the transverse orifice centerline; (iv) the short side shutoff end located at an end of the refractory plate that is opposite of that of the short side orifice end, the short side shutoff end being approximately 1.75 to 2.125 times the maximum design orifice diameter from the transverse orifice centerline; (v) the first and second short side truncate corners being positioned at the short side orifice end of the refractory plate, the first and second short side truncated corners being tangent to a circle that is located at the intersection of the longitudinal centerline and the transverse orifice centerline, the circle having a diameter of approximately 2.50 to 2.75 times the maximum design orifice diameter, in which: (a) the first short side truncated corner extends from the intersection of a first transverse construction line and the first long side until the first short side truncated corner intersects with the short side orifice end, the first transverse construction line being generally perpendicular to the longitudinal centerline and positioned approximately 0.05 to 1.0 times the maximum design orifice diameters inside the short side orifice end; (b) the second short side truncated corner extends from the intersection of the first transverse construction line and the second long side until the second short side truncated corner intersects with the short side orifice end; (vii) the first and second shutoff end truncated corners being positioned at the shutoff end of the refractory plate, the first and second shutoff end truncated corners extending from the intersection of the first and second long sides, respectively, and a third transverse construction line until intersecting the short side shutoff end, the first shutoff end truncated corner being perpendicular to a first shutoff end construction line, the second shutoff end truncated corner being perpendicular to a second shutoff end construction line, in which: the third transverse construction line is approximately 1.125 to 1.50 times the maximum design orifice diameter away from the transverse shutoff centerline toward the short side shutoff end; the first shutoff end construction line extends from the intersection of the longitudinal centerline and a second transverse construction line and through the intersection of the third transverse construction line and a first primary longitudinal construction line, the first longitudinal construction line being 0.25 times the maximum design orifice diameter inside the first long side, the second transverse construction line being approximately 0.375 to 0.5 times the maximum design orifice diameter from the transverse shutoff centerline toward the short side shutoff end; and the second shutoff end construction line extends from the intersection of the longitudinal centerline and a second transverse construction line and through the intersection of the third transverse construction line and a first secondary longitudinal construction line, the second longitudinal construction line being 0.25 times the maximum design orifice diameter inside the second long side.
 27. The moving valve plate of claim 26, wherein each of the first and second sides are positioned at opposite sides of the longitudinal centerline at a distance of 1.75 times the maximum design orifice diameter.
 28. The moving valve plate of claim 26 or 27, wherein the short side orifice end is approximately 1.375 times the maximum design orifice diameter from the transverse orifice centerline.
 29. The moving valve plate of any one of claims 26-28, wherein the short side shutoff end is approximately 2.125 times the maximum design orifice diameter from the transverse orifice centerline.
 30. The moving plate of any one of claims 26-29, wherein the first transverse construction line is approximately 1.0 times the maximum design orifice diameters from the short side orifice end.
 31. The moving plate of any one of claims 26-30, wherein the first transverse construction line is approximately 0.50 times the maximum design orifice diameters.
 32. The moving plate of any one of claims 26-31, wherein the second transverse construction line is approximately 0.5 times the maximum design orifice diameter from the transverse shutoff centerline toward the short side shutoff end.
 33. The moving valve plate of claim 26, wherein each of the first and second sides are positioned at opposite sides of the longitudinal centerline at a distance of 1.50 times the maximum design orifice diameter.
 34. The moving valve plate of claim 26 or 33, wherein the short side orifice end is approximately 1.375 times the maximum design orifice diameter from the transverse orifice centerline.
 35. The moving valve plate of any one of claim 26 or 33-34, wherein the short side shutoff end is approximately 2.125 times the maximum design orifice diameter from the transverse shutoff centerline.
 36. The moving plate of any one of claim 26 or 33-35, wherein the first transverse construction line is approximately 0.5 times the maximum design orifice diameters from the short side orifice end.
 37. The moving plate of any one of claim 26 or 33-37, wherein the third transverse construction line is approximately 1.125 times the maximum design orifice diameters beyond the transverse shutoff centerline.
 38. The moving plate of any one of claim 26 or 33-37, wherein the second transverse construction line is approximately 0.375 times the maximum design orifice diameter from the shutoff centerline.
 39. The moving plate of any one of claims 26-38, further including a first and a second truncated side, wherein the first truncated side extends from the intersection of the first long side and the transverse shutoff centerline to the intersection of the first primary longitudinal construction line and the short side orifice end, and the second truncated side extends from the intersection of the second long side and the transverse shutoff centerline to the intersection of the first secondary longitudinal construction line and the short side orifice end.
 40. The moving plate of any one of claims 26-39, wherein the external corners of the refractory plate are radiused.
 41. The moving plate of any one of claims 26-41, wherein the refractory plate is partially encased in a metal can.
 42. The moving plate of any one of claims 26-41, wherein the refractory plate is encircled by a metal band.
 43. The moving plate of any one of claims 26-42, wherein the refractory plate is made asymmetrical about the longitudinal centerline by displacing one of the orifice end truncations plus or minus 0.125 to 0.25 maximum design orifice diameters along the long side.
 44. An improved stationary plate for controlling a flow of molten metal in a slide gate valve, comprising: a refractory valve plate having an orifice, a first and a second long side, an entrance end, an exit end, a first and a second entrance end truncated corners, and a first and second exit end truncated corners, in which: (i) the orifice is configured to allow molten metal to flow through the refractory plate, the center of the orifice being positioned at the intersection of the longitudinal centerline and a transverse orifice centerline; (ii) the first and second long sides being parallel to the longitudinal centerline, the first and second long sides being positioned at opposite sides of the longitudinal centerline at a distance of approximately 1.125 to 1.25 times the maximum design orifice diameter; (iii) the entrance end is approximately 1.625 to 1.875 times the maximum design orifice beyond a transverse orifice centerline; (iv) the exit end being positioned at an end of the refractory plate that is opposite of that of the entrance end, the exit end being approximately 1.50 to 1.625 times the maximum design orifice diameter from the transverse orifice centerline; (v) the first and second entrance end truncate corners being positioned at the entrance end of the refractory plate, the first and second entrance end truncated corners being tangent to a circle that is located at the intersection of the longitudinal centerline and a first transverse construction line, the circle having a diameter of approximately 2.0 times the maximum design orifice diameter, the first transverse construction line being generally perpendicular to the longitudinal centerline and positioned approximately 1.0 times the maximum design orifice diameters inside the entrance end, in which: (a) the first entrance end truncated corner extends from the intersection of the first transverse construction line and the first long side, extending to be tangent with said circle, extending until the first entrance end truncated corner intersects with the entrance end, (b) the second entrance end truncated corner extends from the intersection of the first transverse construction line and the second long side, extending to be tangent with said circle, extending until the second entrance end truncated corner intersects with the entrance end orifice end; (vii) the first and second exit end truncated corners being positioned at the exit end of the refractory plate, the first and second exit end truncated corners extending from the intersection of the first and second long sides, respectively, and a third transverse construction line until intersecting the exit end, the first exit end truncated corner being perpendicular to a first exit end construction line, the second exit end truncated corner being perpendicular to a second exit end construction line, in which: (a) the second transverse construction line is approximately 1.0 to 1.25 times the maximum design orifice diameter away from the exit end toward the transverse orifice centerline; (b) the third transverse construction line is approximately 0.50 times the maximum design orifice diameter away from the second transverse construction line towards the exit end; (c) the first exit end construction line extends from the intersection of the longitudinal centerline and a second transverse construction line and through the intersection of the third transverse construction line and a first primary longitudinal construction line, the first longitudinal construction line being approximately 0.25 times the maximum design orifice diameter inside the first long side; and (d) the second exit end construction line extends from the intersection of the longitudinal centerline and a second transverse construction line and through the intersection of the third transverse construction line and a first secondary longitudinal construction line, the second longitudinal construction line being approximately 0.25 times the maximum design orifice diameter inside the second long side.
 45. The improved plate of claim 44, wherein the external corners are radiused.
 46. The improved plate of claim 44 or 45, wherein the plate is partially encased in a metal can.
 47. The improved plate of any one of claims 43-46, wherein the plate is encircled by a metal band.
 48. The improved plate of any one of claims 43-47, wherein the entrance end of the plate is defined by a radius of 1.0 maximum design orifice diameters tangent to the corner truncations and the entrance end.
 49. The improved plate of any one of claims 43-48, wherein the plate is made asymmetrical about the longitudinal centerline by displacing one of the exit end truncations plus or minus 0.125 to 0.25 maximum design orifice diameters along the long side. 